The present invention relates to the general field of air propellers. It relates more particularly to a propeller blade pivot.
An air propeller is used in particular in the field of aviation for propelling an aircraft. It is to be found in particular in an aircraft turboprop having a single propeller or two contrarotating propellers.
Typically, each of the propellers of an aircraft turboprop is made up of a plurality of unducted fan blades. The fan blades are of variable pitch, i.e. each blade can pivot about its longitudinal axis (its pitch axis) in order to adapt the orientation of its leading edge to engine speed. The orientation of fan blades (also referred to as the pitch setting) thus constitutes one of the parameters that enable the thrust of the turboprop to be managed.
For this purpose, each propeller blade is generally mounted via its root on a pivot that comprises a rotary support arranged radially in an orifice in a propeller hub while being capable of pivoting in the orifice about a longitudinal axis of the blade.
Each blade pivot also has a blade support that is provided with a socket that is to receive a blade root and also with at least one arm extending laterally relative to the pivot axis of the pivot and carrying a flyweight that forms a counterweight. In the event of an engine failure, the centrifugal force acting on the flyweight positioned on the pivot arm thus serves to ensure that the blade is automatically feathered and that it is held in its feathered orientation.
The main functions of the pivot of a propeller blade are thus to hold the blade (against aerodynamic and centrifugal forces), to hold the flyweights for feathering the blade (essentially against centrifugal force), and to provide the blade with guidance in orientation (mainly against inertial forces).
Blade pivots are generally made of metal, in particular of steel or of titanium. Unfortunately, a large number of blades, in particular in a turboprop having two contrarotating propellers, increases the number of pivots and thus increases the on-board weight.
There thus exists a need to have available a shape for a blade pivot that makes it possible to achieve a saving in weight, in particular given the forces exerted by centrifugal force on the counterweight-forming flyweights.